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Cisco Lean Retail SAP ERP Application Deployment Guide

Cisco Validated DesignJuly 19, 2008

IntroductionThe Cisco Lean Retail SAP ERP solution provides best practices and implementation guidance that optimizes application availability, performance, and security while lowering application ownership costs. Cisco's Lean Retail Architecture provides accelerated application performance and improved access to information. Data center-based applications and hosted managed services can have their performance accelerated to LAN-like speeds. SAP's core business application, Enterprise Resource Planning (ERP), is a business suite that helps retailers manage their inventory, supplier relationships and customer relationships. Cisco's Lean Retail Architecture includes:

Application and collaboration services Integrated networking services Reference network designs

A key Lean Retail integrated network service is the Application Networking Service (ANS). This solution focuses on the ANS components of Cisco Application Control Engine (Cisco ACE) and Wide Area Application Services (WAAS) product families. It provides data center, retail store, and remote end user application optimization services. This collaboration between SAP and Cisco addresses the following SAP Business Suite and NetWeaver deployment challenges:

Reduced capital and operational costs for applications, servers, and networking Recovery time objectives (RTO) and recovery point objectives (RPO) for business continuity Application response time over limited WAN connectionsCorporate Headquarters:

Copyright 2008 Cisco Systems, Inc. All rights reserved.

Cisco Systems, Inc., 170 West Tasman Drive, San Jose, CA 95134-1706 USA

Application, server, network, and service-oriented architecture (SOA) securityThe value of the Cisco Lean Retail is accomplished through four key benefits:

Overview Application AvailabilityWhen an application server fails in a store only that store is impacted. When an application fails in a data center, many stores are impacted. A core tenet of Cisco's Lean Retail Architecture is the centralization of application services. Through server virtualization and load balancing, greater application uptime is achieved. Virtualized server resources in the data center leverage clustering and load balancing to share and distribute load across a larger pool of resources. A single failure does not impact overall accessibility of the application users.

Performance ImprovementTraditionally, retailers use low bandwidth links. Many retailers have hundreds to thousands of stores. The incremental addition of WAN bandwidth per store significantly increases OPEX costs due to economies of scale. Retailers get more for less through the use of virtualized servers, load balancing and WAAS. Performance is significantly improved for the end user (both in stores and across the web). Servers are more fully utilized when loads are balanced across larger clusters. WAN performance is improved by locally caching content and accelerating the TCP protocol.

Increased SecurityRetailers need to comply with industry and regulatory requirements (e.g., PCI, HIPPA, and SOX), to avoid fines and penalties. Security features including encryption, segmentation and authentication address many of these requirements. The Cisco ACE applies stateful inspection rules that explicitly allow or deny specified traffic patterns. The Cisco ACE also uses role based access control to give independent access to both security and load-balancing policies. The Cisco ACE XML Gateway provides a full Layer-7 proxy and includes integrated XML security for web services transactions.

Lowering Application ownership costsMany retailers have hundreds to thousands of stores. Typically they have several servers in each store. For both existing and new applications, the incremental costs per store are significant. By removing servers from the stores, retailers are able to reduce OPEX costs on average of 16%1.

Deploying new applications and capabilities quickly and effectively are key IT metrics that improve an organizations business agility. The Cisco Lean Retail enables more applications to be deployed centrally, cutting down significantly on the time and cost of deployment. Deploying centrally also reduces the costs of opening new stores and of integrating acquisitions. While many Retailers will choose to deploy some applications in the stores, the Cisco Lean Retail improves the capabilities of a central deployment model. To learn more about the Cisco Lean Retail Architecture, refer to: http://www.cisco.com/web/strategy/retail/lean-retail.html

OverviewRetailers look at optimization solutions whenever there is an imminent change ahead-such as a software upgrade-or when a new application is coming on line. It might be a new portal deployment that requires load-balancing or a security policy requiring end-to-end Secure Socket Layer (SSL) support. The WAN is often the biggest consideration when applications change, as bandwidth availability is so limited when dealing with retail's with issues of scale. Changing from an SAPGUI interface to a web browser, for example, can increase bandwidth usage ten-fold. To understand the kinds of changes and upgrades taking place within SAP deployments, it is helpful to understand the SAP application environment and how it has grown over the years. The following section describes the evolution of SAP software, both the business suite and the NetWeaver middleware which supports it.

1. Gartner: Server consolidation can save money 12/20052Cisco Lean Retail SAP ERP Application Deployment Guide

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SAP OverviewSAP OverviewThis section summarizes the SAP application environment. It describes this software architecture in the following sections:

SAP Business Suite, page 3 Pre-NetWeaverStandalone Middleware Applications, page 3 NetWeaver 2004Integration Platform, page 4 NetWeaver 7.0/NetWeaver 2004sComposition Platform, page 4 NetWeaver 7.1Business Process Platform, page 5

SAP Business SuiteSAPs core business application is Enterprise Resource Planning (ERP). It originated in the 1970s as mainframe-based financial accounting software called R/1, and later R/2, where the R stands for real-time data processing. By the 1980s, SAP released its second generation mainframe software R/2 which achieved broad market acceptance for business process automation. Then came the third generation of software, R/3, which provided a client-server approach using a three-tiered architecture of database, application, and user interface. This introduced relational databases, a graphical user interface, and the ability to run on many different platforms.

Figure 1 SAP Business Suites

Since then, SAP has branched out into related business process applications including Product Lifecycle Management (PLM), Supply Chain Management (SCM), Supplier Relationship Management (SRM), and Customer Relationship Management (CRM). These solutions have been further customized across various industry verticals, such as education, finance, Manufacturing, and the like.

Pre-NetWeaverStandalone Middleware ApplicationsTo support these applications, SAP designed various middleware solutions. In SAP terminology, these are not applications so much as technologythe technical underpinnings used to deploy the business suite. This technology was originally released as separate components, as follows:

Web Application Server (WebAS)The ABAP/J2EE platform all SAP applications run on (described in more detail below).

Mobile Engine (ME)Now called the mobile infrastructure (MI), provides support for mobile devices like PDAs through a Java client that connects back to a WebAS.

Enterprise ResourcePlanning (ERP)

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SAP Overview Enterprise Portal (EP)Integrates access to multiple applications and customizes the view based on a users identity.

Business Intelligence (BI)A tool for advanced data analysis and reporting; also known as the business information warehouse (BW).

Exchange Infrastructure (XI)Enables cross-system processes between different applications, such as SAP, non-SAP, ABAP-based, Java-based, and the like. This was later renamed Process Integration (PI) toward the end of 2007.

NetWeaver 2004Integration PlatformThe first release of NetWeaver is referred to as the Integration Platform because it brings together the multiple middleware programs under the NetWeaver umbrella. Each of the middleware applications listed above had its own release cycle and interdependencies creating a cost of ownership issue. To improve this SAP took all of the above components (WebAS, ME, EP, BI, and XI) and integrated them into NetWeaver 2004. This package also introduced new technology including:

Knowledge Management (KM)A framework in EP for document sharing, rating, and updating. Master Data Management (MDM)A solution for consolidating and harmonizing data from

multiple systems.

Composite Application FrameworkApplications built by combining multiple existing functions into a new application using web services. This is the first tool for building composites.

Note Each of these functionswhile integrated into NetWeaver 2004is still a standalone application. There might be an entire farm of servers just for BI, for example.

NetWeaver 7.0/NetWeaver 2004sComposition PlatformOriginally called NetWeaver 2004s, NetWeaver 7.0 provides some updates to the various middleware components described above, but is primarily about enabling a Service-Oriented Architecture (SOA). It includes tools for provisioning web services, either to generate web services within applications or to provide interfaces to older systems that cannot support web services natively. It also includes Enterprise Service Repository (ESR) for storing services and a composition tool so you can take those services and compose applications from them. As such, NetWeaver 7.0 is referred to as the composition platform, a platform for development of xApps, which are SAP composite applications that combine web services and data from multiple systems. See Figure 2.4Cisco Lean Retail SAP ERP Application Deployment Guide

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SAP OverviewFigure 2 NetWeaver 2004s-based Development Platform

Source: https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/4487dd91-0b01-0010-eba1-bcd64196ec6b

NetWeaver 7.1Business Process PlatformWith NetWeaver 7.1, SAP introduces enterprise SOA, making SOA easier to use by applying business logic to the web services that are developed. SOA by itself could theoretically mean exposing every program as services, but this would be unwieldy and difficult to use. The services must be exposed at the correct level to a business process architect who might not understand the program underneath. Thus NetWeaver 7.1 is referred to as the business process platform because it business enables web services, where an enterprise service is an interface to a set of tasks that fit a specific business objective. See Figure 3.

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SAP Server Technology and Data FlowsFigure 3 Migration to Enterprise-oriented SOA Development Environment

Source: SAP TechEd 2007 SOA 101

Summary

In summary, SAP has a suite of business applications complemented by NetWeaver middleware. Over the last several years, NetWeaver has evolved from the integration of middleware applications to an enterprise SOA platform that provides for rapid development of composite applications. These composite applications armed with right-sized enterprise services make it possible to rapidly improve business processes and be more responsive to market demands.

SAP Server Technology and Data FlowsThis section provides a technical overview of the SAP server architecture and describes how it relates to a server load-balancing solution. The following topics are addressed:

SAP Web Application Server, page 7 Client-Server Flows, page 7 Server-to-Server Flows, page 8 SAP Server Scaling, page 8 Server Load-Balancing with Cisco ACE, page 10

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SAP Server Technology and Data FlowsSAP Web Application ServerThe foundation for SAP applications is the SAP Web Application Server (WebAS). It is the set of programs and tools which interface with the operating system, database, communication protocols and presentation interfaces. This software enables SAP applications to have the same functionality and work the same way no matter what operating system is installed and whatever database is used. The web server is also integrated into the application server so SAP does not rely on other web servers such as IIS or Apache. WebAS runs on most operating systems such as Windows, Linux, and AIX. It maintains database independence by using Open SQL/SQLJ to interface with various databases such as Microsoft SQL Server, MySQL, IBM DB2, and Oracle. Also note that each SAP application generally has its own database. For example, a production system landscape composed of SAP ERP, BI, and CRM would consist of three separate databases.WebAS uses two types of programming languages, either Advanced Business Application Programming (ABAP), Java 2 Platform, Enterprise Edition (J2EE) or both. ABAP is the original programming language created by SAP and is similar to COBOL. Java was introduced more recently. ABAP tends to be used more on the business applications, like ERP, while Java is typical for middleware components like the SAP Enterprise Portal. ABAP and J2EE can be installed alone or together as a dual stack.Figure 4 illustrates the components of a dual-stack SAP Web AS and some of the common data flows with typical clients and application servers.

Figure 4 SAP Communications Patterns

Client-Server Flows

SAPGUI clients are exclusively ABAP and are received by the ABAP dispatcher listening to port 32xx. The dispatcher then forwards the request to the best available ABAP work process. ABAP-based web

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SAP Server Technology and Data Flowsrequests are first received by the Internet Communication Manager (ICM)which listens for HTTP on port 8000 by default, but can be configured to use any port. The ICM then parses the URL to determine if the session should be routed to the ABAP or Java dispatcher. While Java web sessions can also be routed through the ICM, in other casesparticularly in Java only servers like the SAP EPthe web sessions connect directly to the Java Dispatcher, which is listening on 5XX00 for HTTP and 5XX01 for SSL.For a complete listing of ports used by SAP, refer to the following URL:https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/4e515a43-0e01-0010-2da1-9bcc452c280b.

Server-to-Server FlowsCommon application-to-application flows include the following:

Remote Function Call (RFC)The RFC is a SAP protocol for interprocess communication between systems. The RFCs enable you to call and execute predefined functions in a remote system, or in the same system. The RFCs manage the communication process, parameter transfer, and error handling.

SAP Java Connector (JCo)/RFCThe SAP JCo is an adapter that the Java-based servers use to execute RFC communications with ABAP servers. In the J2EE Engine the RFC functions are implemented by the JCo RFC Provider service, which is used for processing ABAP-to-Java requests. A feature is also provided for receiving calls from the SAP systems. This is done by registering the J2EE Engine as a RFC destination.

XML/SOAP Web ServicesStandard XML/SOAP messages are used for SOA communications. This is currently an area of growth for SAP as core processes are exposed as web services and leveraged in new ways with composite applications like the SAP xApps family.

SAP Server Scaling

SAP application servers scale by separating functions into a Central Instance (CI) and Dialog Instance (DI). See Figure 5. The CI contains the message and enqueue servers and is responsible for queuing and database locks, while the DIs perform the actual processing of the application. There is a single CI. For high availability, it is deployed in active/standby mode using the clustering software of the underlying platform. Processing capacity is increased by adding DIs and this is where load-balancing applies.8Cisco Lean Retail SAP ERP Application Deployment Guide

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SAP Server Technology and Data FlowsFigure 5 SAP Server Scaling

Source:https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/c3d9d710-0d01-0010-7486-9a51ab92b927

Each SAP application scales in this way. Figure 6 illustrates the SAP server farmmultiple business and middleware applications, each with their own CI cluster, DI servers and database servers. Each of these are separate entities where various application and security optimizations may apply.

Figure 6 SAP Server Farm

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Data Center DesignServer Load-Balancing with Cisco ACELoad-balancing SAP with the Cisco ACE is focused on web transactions (not SAPGUI or RFC). The process proceeds as follows:1. For client-server traffic, the client DNS request resolves to a virtual IP (VIP) address located on the

Cisco ACE rather than the real server itself. The Cisco ACE then distributes the load to real servers using a configured server selection method such as weighted round robin. In most cases once a client session is directed to a server, ACE sticks all subsequent requests to that same server, typically using a cookie. Health probes are used to take non-responsive servers out of rotation.

2. For application-to-application web services traffic, the application first generates a request for the web services definition language (WSDL). This request is load balanced to a server, either the real server itself or on a central repository such as SAP's ESR. When the application receives the WSDL, it locates the URL to the service and generates a new request using that URL. This URL resolves to a VIP address on the Cisco ACE which in turn load-balances the request to a real server. Typically this web services request is a single request and therefore persistence is not required. If necessary, persistence can be provisioned in the same way as client-to-server sessionsthe HTTP header for web services requests contains the saplb_* cookie (discussed below) and will also accept inserted cookies.

Classic SAP is not load-balanced by the Cisco ACE. Instead, it is load-balanced by the message server itself using a redirect approach. A typical process proceeds as follows:1. A SAPGUI client connects directly to the message server. 2. The message server replies back to the client with an IP address and port for the best server instance. 3. The SAPGUI client connects to the DI directly.

Data Center DesignThis section describes how to design the data center architecture for a server farm using virtualization. It covers the following topics:

SAP Portal Design, page 10 Infrastructure Consolidation with Virtualization, page 13 Security and Server Load-Balancing Integration, page 15 Segmenting Security and Load Balancing with Roles-Based Access Control, page 16 Segmenting Content Owners with Roles-Based Access Control, page 18 Virtualization Design Considerations, page 19

SAP Portal DesignFigure 7 shows an SAP portal design. There are three security zones, each separated by firewalls:

The first zone is the outer DMZ and contains an application gateway. It is either clustered or load-balanced depending on the load requirement.

The second zone is the inner DMZ and includes the customer portal and a web gateway to backend content. A customer, for example, might click on a link in the portal that requires an ERP transaction. The portal redirects the browser to the Internet Transaction Server (ITS). The ITS WGate is a web front-end that presents HTML pages to the user and links to the ITS AGate. The ITS 10Cisco Lean Retail SAP ERP Application Deployment Guide

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Data Center DesignAGate translates the pages to R/3 transaction screens and forwards them to the ERP application server for processing. For more information on ITS, refer to the following URL: http://searchsap.techtarget.com/sDefinition/0,,sid21_gci822867,00.html.

Note There could be many variations of this type transaction, such as a chain of web services requests from the portal to a composite application, to a newer backend with a dual-stack of ABAP and Java. Exchange Infrastructure (XI) is also commonly in the mix. It translates between ABAP and Java environments, or web services and non-web services enabled hosts. (In this example, the Java systems are shown in orange and the ABAP systems in blue.)

The third zone includes the corporate federated portal along with the backend systems and NetWeaver applications such as BI. This is the high-security zone that contains critical enterprise data.11Cisco Lean Retail SAP ERP Application Deployment Guide

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Data Center DesignFigure 7 SAP Portal Deployment

For more information refer to SAP TechEd 2007: UP204 Best Practices for Building a Portal Infrastructure at the following URL: http://www.sapteched.com/usa/

In each zone, there is a requirement for some mix of security, server load-balancing (SLB), and SSL termination infrastructure. When built with high availability (HA) in mind, the amount of hardware required starts to multiply. Firewalls are required at each tier and if they must be redundant there will be two of each. Another pair of load-balancers is required in the inner DMZ and high security area. If the application gateway in the outer DMZ becomes a bottleneck, a pair of load-balancers will be required for it as well. While this diagram focuses on the portal, in actual implementation there are many other components that might be included in a given customer deployment such as additional business applications and composite applications. Some business applications, such as Supplier Relationship Management (SRM), are necessarily oriented toward external communications. These systems might be added into the inner DMZ. Composite applications might also be deployed in this zone to provide information to external

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Data Center Designclients or partners while shielding the backend from direct access. These applications might require their own dedicated load-balancers so that the application owners maintain control of their policies. Similarly, backend applications that use dual ABAP/Java stacks might also require load-balancing. Figure 8 shows how the hardware required for this design can grow over time.

Figure 8 Deployment with Dedicated Firewalls and Load-Balancers

Infrastructure Consolidation with VirtualizationThe amount of infrastructure required to deploy this solution can be sharply reduced through virtualization. Each virtual context on a Cisco Firewall Services Module (FWSM) or Cisco Application Control Engine (ACE) has its own configuration file, statistics, resources, and rules for administrative access. With the modules deployed in HA mode, configuration files need only be maintained on the active context as replication is automatic. As a result, each virtual context acts as a separate device that is much more scalable since it inherits the performance and high availability configurations built into the physical device and can be deployed without ordering parts, wiring, etc. This greatly simplifies the design and makes it extremely easy and cost effective to grow additional server farms with a high degree of reliability. Figure 9 shows a single pair of Cisco Catalyst 6500 switches, each equipped with a Cisco FWSM and Cisco ACE module. They are setup in a pair to achieve high availability with stateful failover.

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Data Center DesignFigure 9 Infrastructure Consolidation with Virtualization

The Cisco FWSM is used to segment the network into security zones using three virtual contexts and within each zone a Cisco ACE virtual context is allocated to each content owner. This way each content owner has their own virtual context that inherits all of the high availability and high performance properties of the underlying the Cisco ACE platform without the risk of configuration errors affecting other users.Figure 9 illustrates three different ways the Cisco ACE contexts can be deployed in this fashion. In the outer DMZ and inner DMZ, the Cisco ACE is deployed like another server, sitting on the same VLAN as the servers in one-arm mode. Traffic comes into a virtual IP address located on the Cisco ACE and the Cisco ACE sends it back out onto the same network to a Layer-2 adjacent server. Note that in this case the Cisco ACE is not in-line, so a method such as policy-based routing or source NAT must be used to ensure the load-balanced traffic is returned through ACE and not directly to the default gateway. An example of source-NAT configuration is shown in the TCP reuse section below.

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Data Center DesignIn the high security zone, two other deployment options are shown for the Cisco ACE virtual contexts. The corporate portal shows the Cisco ACE context in-line to add another layer of security, now in control of the content owner. Any connection to the corporate portal servers must now traverse the Cisco ACE and pass the security policies deployed in it. The third option is shown with the BI server farm. It shows the database (formerly assumed to be Layer-2 adjacent to the servers) on a separate segment on the Cisco ACE. Now BI application servers communicating to the database are limited to only relevant communications, typically SQL. This prevents a compromised application server from being able to scan and attack other services on the database server that may be vulnerable. Note that when an application server communicates with a database through the Cisco ACE, there may be a need for extended flow timeouts. Usually, this is not an issue but some implementations optimize performance by pre-opening the database connection, making database opens quicker and more efficient. The Cisco ACE, however, times out a flow after one hour by default. This can break communications if the server does not attempt to reestablish the connection. The example below shows how to set the inactivity timeout to infinity so that these connections are never timed out. This configuration should be applied as specifically as possible so that stale flows do not accumulate. In this example, the timeout is set only for flows targeting port 1521 and originating from the server side VLAN, which in this example is VLAN 10. parameter-map type connection DB set timeout inactivity 0

class-map match-all DB-class match port tcp eq 1521

policy-map multi-match DB-policy class DB-class connection advanced-options DB

interface vlan 10description server side interface service-policy input DB-policy

Security and Server Load-Balancing IntegrationAlternatively, when using the virtualization and integrated security functions of the Cisco ACE, the scenario described above could be further consolidated onto the Cisco ACE module with Cisco ACE virtual contexts deployed in place of the Cisco FWSM virtual contexts. This is the same design, only now with a single pair of the Cisco ACE modules hosting all of the virtual contexts: some security only, some load balancers, and some a mix. In smaller environments, the design can be further streamlined by integrating the security and load-balancing policies onto a single context in each zone and using role-based access to separate content owners and security functions. So in this case, a single context in each zone has both firewall rule sets, as well as load-balancing and SSL policies for multiple content owners. This reduces latency because the packet need only be examined once to apply the various policies. Note, however, that in larger deployments this style topology becomes more complex instead of less. When there are multiple content owners, it is more straightforward to divide the functions and just provide each owner with their own context. Once the network is established and running, there might be strict controls on changes to the environment in order to prevent any possible disruption. This can result in delays to application owners who want to get their applications online quickly. Giving the application owners a dedicated virtual context reduces risk to the existing configuration that is already working. It also simplifies the configuration file because there are fewer policies and server definitions. 15Cisco Lean Retail SAP ERP Application Deployment Guide

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Data Center DesignSimilarly, show commands only reflect the connections actually going to the owner's servers. As a result, the topology in Figure 10 should be used for smaller scale deployments. Figure 10 shows the above topology streamlined using only three Cisco ACE contexts in each module.

Figure 10 Deployment with Integrated Security, Load-balancing and SSL

Segmenting Security and Load Balancing with Roles-Based Access ControlWhen security and load-balancing functions coexist on the same context as shown in the preceding example, there might be a need to further segment administrative control if different teams are responsible for these functions. With roles-based access control (RBAC) enabled on the Cisco ACE, the security administrator can only access the security portion of the configuration. Similarly, the server administrator can only access load-balancing related functions.The Cisco ACE comes prepackaged with a number of predefined roles. The SLB-Admin, Security-Admin roles are shown in the configuration that follows. The load-balancing commands are accessible to the SLB-Admin and security-related commands are associated with the Security-Admin role.

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Data Center DesignCisco ACE-1/sap# sh role

Role: SLB-Admin (System-defined) Description: Administrator for all load-balancing features Number of rules: 8 ---------------------------------------------

Rule Type Permission Feature ---------------------------------------------

1. Permit Create real 2. Permit Create serverfarm 3. Permit Create vip 4. Permit Create probe 5. Permit Create loadbalance 6. Permit Create nat 7. Permit Modify interface 8. Permit Create config_copy

Role: Security-Admin (System-defined) Description: Administrator for all security features Number of rules: 7 ---------------------------------------------

Rule Type Permission Feature ---------------------------------------------

1. Permit Create access-list 2. Permit Create inspect 3. Permit Create connection 4. Permit Modify interface 5. Permit Create aaa 6. Permit Create nat 7. Permit Create config_copy

These roles can be used to easily divide up administrative responsibilities without a lot of configuration required. In this way, security personnel can manage access control without the possibility of mistakenly disrupting the server load-balancing configuration and the same applies to SLB admin. Applying these predefined roles is simple; in the following example:

Mark is assigned the role of security admin. Tom is assigned as the SLB admin.

Example configuration:user Mark pass cisco123 role Security-Admin user Tom pass cisco123 role SLB-Admin

When Mark logs in and tries to configure an rserver (an SLB task), he is blocked:CE-1/sap# conf tEnter configuration commands, one per line. End with CNTL/Z.Cisco ACE-1/sap(config)# rserver xyz ^

% invalid command detected at '^' marker.

Only commands permitted by the security role can even be seen by Mark:

Cisco ACE-1/sap(config)# ?Configure commands: aaa Configure aaa functions access-group Activate context global access-list access-list Configure access control list arp Configure ARP banner Configure banner message class-map Configure a Class map 17Cisco Lean Retail SAP ERP Application Deployment Guide

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Data Center Designdo EXEC command end Exit from configure mode exit Exit from configure mode interface Configure an interface ip Configure IP features ldap-server Configure LDAP related parameters no Negate a command or set its defaults parameter-map Configure a parameter map policy-map Configure a policy map radius-server Configure RADIUS related parameters service-policy Enter service policy to be applied to this context snmp-server Configure snmp server ssh Configure SSH parameters tacacs-server Configure TACACS+ server related parameters timeout Configure the maximum timeout duration username Configure user information.

Similarly, Tom, the SLB admin, sees only commands related to his role:Cisco ACE-1/sap# conf tEnter configuration commands, one per line. End with CNTL/Z.Cisco ACE-1/sap(config)# ?

Configure commands: access-group Activate context global access-list arp Configure ARP class-map Configure a Class map do EXEC command end Exit from configure mode exit Exit from configure mode interface Configure an interface ip Configure IP features no Negate a command or set its defaults parameter-map Configure a parameter map

policy-map Configure a policy map probe Configure probe rserver Configure rserver script Configure script file and tasks serverfarm Configure serverfarm service-policy Enter service policy to be applied to this context snmp-server Configure snmp server ssh Configure SSH parameters timeout Configure the maximum timeout duration username Configure user information.Cisco ACE-1/sap(config)#

Segmenting Content Owners with Roles-Based Access ControlRoles-based access control can also be used to support multiple content owners on a single context with the use of domains. The SCM administrators, for example, could be given full control over their own load-balancing domain within the context while being prevented from altering configurations in other domains.The following configuration example shows that Tom, the SCM administrator, is allowed to modify only the SCM policy-map. A domain, SCM, is created, and the policy-map called SCM-policy is added to that domain, and then Tom is associated to the domain.domain SCM 18Cisco Lean Retail SAP ERP Application Deployment Guide

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Data Center Designadd-object policy-map SCM-policyusername Tom password cisco123 role SLB-Admin domain SCM

Now, when Tom attempts to edit a policy not included in his domain, he is blocked (as shown in the following configuration input example) when he attempts to edit portal policy. However, when Tom edits the allowed SCM policy, the action is permitted:Cisco ACE-1/sap(config)# policy-map type loadbalance first Portal-policyError: object being referred to is not part of User's domainCisco ACE-1/sap(config)# policy-map type loadbalance first SCM-policy Cisco ACE-1/sap(config-pmap-lb)#

Virtualization Design ConsiderationsThis section shows how to deploy a SAP server farm like the one above using the Cisco Catalyst 6500 and related service modules. Figure 11 shows a Cisco ACE module with an Admin context and three contexts for SAP servers. Each context is allocated VLAN interfaces per the design requirement.

Figure 11 Cisco ACE Module Layout for SAP Server Farm

VLAN100

Catalyst6500

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Data Center DesignFigure 12 shows how these contexts and VLANs fit within the overall data center architecture.

Figure 12 Data Center Architectural View

The following are important to note about the design illustrated in Figure 12: Only VLANs 20, 40, and 60 will be trunked to the access switches where the servers in each zone

ultimately connect. All the Cisco ACE VLANs are trunked between the two aggregation switches (including the failover

trunk VLANnot shown), The Cisco ACE contexts are shown to be all primary on the left and standby on the right, but these

positions can be alternated in order to balance the processing load between the two Cisco ACE modules for an active-active configuration.

The Cisco Network Analysis Module (NAM), shown by an icon in the upper corner of each aggregation switch, provides centralized visibility into all VLANs for troubleshooting and performance monitoring. Remote SPAN (RSPAN) can be used on the access switch to provide greater visibility to the servers.

20

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Cisco ACE Module Implementation and Configuration This design provides the flexibility for intrusion detection systems (IDS) or intrusion prevention systems (IPS) to inspect the traffic. Even end-to-end SSL traffic can be secured in this way. For example, the outer DMZ context can decrypt the SSL and send it to the proxy. When the proxy sends HTTP down to the next context, IDS inspection can be applied to the clear text on VLAN 30, then the traffic can be encrypted again toward the servers on the inner DMZ context.

All the Cisco ACE contexts are shown in routed mode. The Admin context is not shown. When chaining multiple contexts together in this way, routed mode provides a stable and loop-free environment.

This design shows dedicated VLANs for servers. The inter-context VLANs (30 and 50) can be used instead, butbecause there is no shortage of VLAN interfaceshaving a dedicated interface for the servers might allow more flexibility with the access restrictions.

This document does not cover all configurations associated with an HA design, but does highlight the configurations required for accomplishing the tasks specific to the SAP deployment.

Cisco ACE Module Implementation and ConfigurationThis section describes the steps required to configure the Cisco ACE module for a SAP deployment using the above scenario as an example. It is based on testing with SAP ERP 6.0 and SAP NetWeaver 7.0. It includes the following topics:

Admin Context Setup, page 22 Baseline User Context Configuration, page 22 Security, page 23 Server Farms, page 24 Basic Load Balancing, page 24 Health Monitoring, page 25 Health Monitoring for Web Services, page 26 Session Persistence, page 27 SSL Termination, page 31 HTTP Header Rewrite (Cisco ACE 2.0), page 32 HTTP Header Insert, page 33 Persistence Rebalance, page 33 Redirect Server, page 33 Impact of TCP Reuse and SSL Termination on Server CPU, page 34 Backend Encryption, page 34 SSL Reuse (Cisco ACE 2.0), page 35 TCP Reuse, page 36 WAN Tuning with Cisco ACE, page 38 Optimization Summary, page 3921Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationAdmin Context SetupThe first step in setting up the Cisco ACE is to allocate a VLAN in the Cisco Catalyst 6500 and to set up the Admin context. The steps that follow describe this process.

Step 1 First create the VLANs on the Cisco Catalyst and assign them to the Cisco ACE.Cisco Catalyst 6500 configuration:vlan 10vlan 20! etc.svclc vlan-group 1 10,20,30,40,50,60,100

Step 2 On the Cisco ACE, define the three SAP virtual contexts and their VLANs.Cisco ACE Admin context configuration:context InnerDMZ allocate-interface vlan 10 allocate-interface vlan 20 allocate-interface vlan 30context OuterDMZ allocate-interface vlan 30 allocate-interface vlan 40 allocate-interface vlan 50context Backend allocate-interface vlan 50 allocate-interface vlan 60

Baseline User Context ConfigurationThere are a few things that must be configured on any user context, without regard to the load-balancing or security policies. These are as follows:

Since these are routed contexts, the interfaces need IP addresses. (Alias addresses for HA are not shown, but are required for a redundant scenario.)

Static routes and default routes are required. A management access policy must be assigned to an interface, if there is to be access to the context

outside of the Admin context (this is recommended if each context has a different owner, since the Admin context has unrestricted access to all the other contexts). VLAN 20 is selected in this example.

An access control list (ACL) must be defined on each interface. This is covered in Security, page 23.Here is an example of the outer DMZ context configuration:class-map type management match-any REMOTE-ACCESS description "Define Allowed Mgmt Traffic" 2 match protocol http any 3 match protocol https any 4 match protocol telnet any 5 match protocol ssh any 6 match protocol xml-https any 7 match protocol snmp any 8 match protocol icmp any22Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and Configurationpolicy-map type management first-match REMOTE-MGMT class REMOTE-ACCESS permit

interface vlan 10 description outerDMZ outside interface ip address 10.10.1.1 255.255.255.0 no shutdown

interface vlan 20 description Proxy VLAN ip address 10.10.2.1 255.255.255.0 service-policy input REMOTE-MGMT no shutdown

interface vlan 30 description outer DMZ inside interface ip address 10.10.3.1 255.255.255.0 no shutdown

ip route 0.0.0.0 0.0.0.0 10.10.1.2

SecurityEach interface on the Cisco ACE applies stateful inspection rules that explicitly allow or deny specified traffic patterns. Since the ACLs are stateful, the return path for the traffic need not be specified. The syntax is standard Cisco extended ACL configuration commands using access-list commands to create the rules and access-group commands to apply the rules to interfaces. For example, on the outer DMZ, context traffic could be limited to HTTP and SSL destined to the VIP address for the proxy. All other traffic is denied by default. Example configuration:access-list VIP line 10 extended permit tcp any eq www host 10.10.2.10 access-list VIP line 20 extended permit tcp any eq https host 10.10.2.10

interface vlan 10 description outerDMZ outside interface access-group input VIP

On the inner DMZ, since the only traffic coming in should be coming from the proxy, the traffic could be limited to HTTP from the proxy real address, destined to the VIP address for the customer portal. Similar entries could be made for traffic to the Composite Application VIP address and the SRM VIP address. All other traffic is denied by default.Example configuration:access-list PROXY_VIP line 10 extended permit tcp host 10.10.2.10 eq www host 3.3.3.3

interface vlan 30 description innerDMZ outside interface access-group input PROXY_VIP23Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationServer FarmsEach real server must be defined as a rserver and again in a server farm, if there is to be port translationsuch as port 80 to 50000defined in the serverfarm configuration. Probes can be attached to the rserver or the server farm. Probes are described in the Health Monitoring, page 25. The following configuration example shows a single system hosting two server farms - one for HTTP (50000, 50200) and another for HTTPS (50001, 50201):rserver host SAP-EP description "SAP Enterprise Portal" ip address 169.145.90.11 inservice

serverfarm host EP-HTTP rserver SAP-EP 50000 inservice rserver SAP-EP 50200 inservice

serverfarm host EP-HTTPS rserver SAP-EP 50001 inservice rserver SAP-EP 50201 inservice

Basic Load BalancingTo load balance connections to a server farm, there need to be at least four elements in place: a virtual IP address (VIP) /port, a load balancing policy, a multi-match policy, and a service-policy on the interface where the requests come in. Below is an example of the minimum components to accomplish basic load balancing to the EP-HTTP server farm shown above. The example has the following:

A class map, HTTP-VIP, set up to match incoming port 80 requests to a VIP of 169.145.90.116. A load balancing policy, EP-HTTP-policy, that sends requests to the EP-HTTP server farm. A multi-match policy, SLB-policy, that links the class-map to the load balance policy. The

multi-match policy is tied to an interface, VLAN 200, where the requests originate.

class-map match-any HTTP-VIP match virtual-address 169.145.90.116 tcp eq www

policy-map type loadbalance first-match EP-HTTP-policy class class-default serverfarm EP-HTTP

policy-map multi-match SLB-policy class HTTP-VIP loadbalance vip inservice loadbalance policy EP-HTTP-policy

interface vlan 30 description innerDMZ outside interface service-policy input SLB-policy24Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationMultiple VIP class-maps can be assigned to a single multi-match policy. So if we want port 80 traffic to go to a different server farm than port 443 traffic, we create another class-map that matches the same VIP but on port 443 instead of port 80. Then create a load-balance policy that maps to the HTTPS server farm and add these pieces to the multi-match policy with an additional class statement.

class-map match-any HTTPS-VIP match virtual-address 169.145.90.116 tcp eq https

policy-map type loadbalance first-match epSAP-s class class-default serverfarm EP-HTTPS

policy-map multi-match SLB-policy class HTTP-VIP loadbalance vip inservice loadbalance policy EP-HTTP-policy class HTTPS-VIP loadbalance vip inservice loadbalance policy epSAP-s

This shows the basics of the configuration process to achieve load balancing: rserver, server farm, VIP class map, loadbalance policy, multimatch policy, and service policy. As shown below, there are a number of enhancements to this baseline to meet the needs of an SAP deployment.

Health MonitoringTo achieve high availability in the server farm, the load-balancer needs a way to determine whether the server is able to properly service a client request. Ideally, the probe should capture all information necessary to verify this capability. Sending a ping verifies the host is available, but not the application. A web page probe verifies that the application is running but not necessarily its connection to the database. It is possible to create multiple probes testing the state of the application as well as the database. However, in the case of the SAP EP, a database connection is required to deliver the portal logon page. A single probe to the /irj/portal URL verifies host, application, and database availability. The example configuration that follows illustrates configuring a probe to the irj/portal URL that expects a 200 OK from the server in order to consider the server as up. If the database is unable to respond to the application server, it will not return a 200 OK to this probe and will ultimately be taken out of service. Note that here since the two servers are running on the same physical host with different port numbers, the probes are assigned as subcommands to the rserver command rather than the serverfarm command. When all the servers share the same port number, the probe need only be assigned once for the entire server farm.

Example configuration:probe http PORTAL-50000 description http-probe port 50000 interval 20 passdetect interval 10 request method get url /irj/portal expect status 200 200

probe http PORTAL-50200 description http-probe port 50200 interval 20 passdetect interval 10 request method get url /irj/portal expect status 200 20025Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and Configurationserverfarm host EP-HTTP rserver SAP-EP 50000 probe PORTAL-50000 rserver SAP-EP 50200 probe PORTAL-50200

Health Monitoring for Web ServicesWhen load-balancing SOA web services connections, a good URL to use is /nwa. This is the NetWeaver Web Administrator service. As in the preceding scenario with /irj/portal, this service only works if the host, application, and database are up and running. When the probe was set up initially, however, it failed because a 200 response code was expected, but not received. Be sure to check if there are 302 redirects occurring, since the application might direct you to another URL in order to do the proper health check. One way to test this is to log-in to the Cisco ACE, Telnet to the port to which the server is listening, and send the URL information. The example below shows what was seen when sending the /nwa to the composite application. In addition to sending GET /nwa, it was also necessary to send HTTP/1.1 and then the host address.

Cisco ACE/dc# telnet 169.145.90.16 50100Trying 169.145.90.16...Connected to 169.145.90.16.Escape character is '^]'.GET /nwa HTTP/1.1Host: 169.145.90.16

HTTP/1.1 302 Foundserver: SAP NetWeaver Composition Environment 7.1 / AS Java 7.1content-type: text/htmllocation: http://169.145.90.16/webdynpro/dispatcher/sap.com/tc~lm~itsam~co~ui~nwa~localnavigation~wd/NWAAppcontent-length: 0date: Fri, 30 Nov 2007 04:15:04 GMT

The server responds with a 302 instead of 200. If a probe is sent to this URL and expects a 200 OK to come back, it will fail. Here, the server shows us the redirect location to use (as highlighted in the above example). Below is the result when running the test again with the new location:Cisco ACE/dc# telnet 169.145.90.16 50100Trying 169.145.90.16...Connected to 169.145.90.16.Escape character is '^]'.GET /webdynpro/dispatcher/sap.com/tc~lm~itsam~co~ui~nwa~localnavigation~wd/NWAApp HTTP/1.1Host: 169.145.90.16

HTTP/1.1 200 OKserver: SAP NetWeaver Composition Environment 7.1 / AS Java 7.1date: Fri, 30 Nov 2007 04:12:38 GMTcontent-length: 0set-cookie: saplb_*=(J2EE13893320)13893353; Version=1; Path=/set-cookie: JSESSIONID=6_KhDb-p3MDOrRodWCcx13pvJ5iAkcGOFgHp_tMA_SAP; Version=1; Path=/

The resulting probe configuration is:probe http BACK-1 port 50100 interval 2026Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and Configuration passdetect interval 10 request method get url /webdynpro/dispatcher/sap.com/tc~lm~itsam~co~ui~nwa~localnavigation~wd/NWAApp expect status 200 200

Session PersistenceOnce an SAP user logs into an instance of the portal, all subsequent requests must be sent to that same server. If each new request from a client is load-balanced to a different server, within a few clicks the session is broken. To ensure session persistence, some form of stickiness must be configured either based on the user's IP address or a session cookie. Stickiness is one of many resources in the Cisco ACE that can be allocated to a virtual context. Cisco ACE supports count limits on connections, xlates, management sessions, proxy connections, ACL memory, and regexp. It also supports rate-limits on connections per second, fixup per second, bandwidth, SSL connections per second, MAC-miss rate, and management traffic rate. Generally, if there is no specific configuration for resource allocation, each virtual context on a Cisco ACE has access to all the resources. Stickiness, however, must be configured explicitly on the Admin context before persistence can be configured on an individual context. In this example, each virtual context that is a member of the PERSIST resource class is entitled to at least 20 percent and no more than 20 percent of the total sticky resources in the Cisco ACE. There are no limitations on other Cisco ACE resources.Example configuration:resource-class PERSIST limit-resource all minimum 0.00 maximum unlimited limit-resource sticky minimum 20.00 maximum equal-to-min

context InnerDMZ member PERSIST

Once sticky resources have been allocated to a context, persistence can be configured on that context. Here, we look at three methodssource IP, cookie insert, and cookie learning. Source IP address requires no Layer 7 inspection and or SSL termination, but is ineffective if there are proxy servers. Cookie-based persistence methods require an inspection of the HTTP header and therefore require SSL termination. Cookie insert can be done without any knowledge of how cookies are used by the server. As such, it is a generic method that can be used across the board. Cookie learning works when you know which cookie to base the persistence on. The only real advantage of using it with SAP is the cookie value contains the node ID of the server which enables you to easily see by looking at the client's cookie what node the client has connected to. Each of these methods were tested and are described below.

Source IP Persistence

Source IP is the simplest method to assert persistence because it requires no inspection of the HTTP header. Even SSL encrypted sessions carry the IP address in the clear, so source IP sticky can be applied without terminating SSL. To configure it on the Cisco ACE, first create a sticky server farm (which references one of the real server farms configured above) and then assign it to the loadbalance policy.Example configuration:sticky ip-netmask 255.255.255.255 address source ep-sourceIP timeout 10 serverfarm EP-HTTP27Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and Configurationpolicy-map type loadbalance first-match basic-slb class class-default sticky-serverfarm ep-sourceIP

To see which server a client has to, use the show sticky data client x.x.x.x command. Example:Cisco ACE-1/sap# show sticky data client 12.20.15.15sticky group : ep-stickytype : IP timeout : 10 timeout-activeconns : FALSE sticky-entry rserver-instance time-to-expire flags ------------------+----------------------+--------------+-------+

202641167 ep1:51000 599 -

Cookie Persistence

Persistence based on the source IP address can work well, but if the clients go through a proxy, they will all be sent to the same server, and the load is not balanced evenly. Cookie sticky avoids this problem by maintaining persistence at the session level based on the value of a cookie in the HTTP header. Cisco ACE can either learn the cookie set by the application or it can insert its own cookie into the header.Cookie insertion is usually a good option if it is not clear which cookie should be used for load-balancing. It is not disruptive to the SAP server and can be counted on reliably for session persistence. When you create a static sticky entry, Cisco ACE places the entry in the sticky table immediately. Static entries remain in the sticky database until you remove them from the configuration. The sticky configuration for cookie insert is similar to source IP stickyyou create a sticky server farm and apply it to the loadbalance policy.Example configuration:sticky http-cookie ace_cookie ep-insert cookie insert browser-expire replicate sticky serverfarm EP-HTTP

policy-map type loadbalance http first-match ep-policy class class-default sticky-serverfarm ep-insert

To see the sticky database on inserted cookies, use the static keyword:switch/SAP-Datacenter# show sticky data staticsticky group : ep-inserttype : HTTP-COOKIEtimeout : 1440 timeout-activeconns : FALSE sticky-entry rserver-instance time-to-expire flags ---------------------+--------------------------------+--------------+-------+

8406590389602098862 SAP-EP:50000 never sticky group : ep-inserttype : HTTP-COOKIEtimeout : 1440 timeout-activeconns : FALSE sticky-entry rserver-instance time-to-expire flags ---------------------+--------------------------------+--------------+-------+

18052788081821769859 SAP-EP:50200 never

Note When static cookies are used there will only be one entry in the cookie database per real server. So, if ace-cookie is the only cookie defined and there are two servers, there will only be two entries in the sticky database, even if there are thousands of user sessions.28Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationDynamic Cookie Learning

Dynamic cookie learning is another option for keeping the SAP session persistent. The sticky table can hold a maximum of four million dynamic entries (four million simultaneous users). The key is choosing the right cookie name. Figure 13 shows an analysis of an SAP HTTP header and the cookies that are present after logging-in to the site.

Figure 13 SAP Cookies

SAP sets a number of cookies for various purposes (note the ace_cookie was set by Cisco ACE using cookie insert, not SAP), but the saplb_* cookie is set by SAP specifically for load-balancers. It has the format saplb_=()[].Here, the cookie value also helps to verify which server instance and physical node you are connected to. For more information, refer to the following URL:http://help.sap.com/saphelp_erp2005vp/helpdata/en/f2/d7914b8deb48f090c0343ef1d907f0/frameset.htm

The configuration process for cookie learning is similarwith a few changes in the syntax. Example configuration:ssticky http-cookie saplb_* ep-cookie replicate sticky serverfarm EP-HTTP

policy-map type loadbalance http first-match ep-policy class class-default sticky-serverfarm ep-cookie

Note In the above examples, the replicate sticky command is used so that the cookie information is replicated to the standby Cisco ACE context. With this implementation, session persistence is maintained in the event of a failover. The default timeout is one day.29Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationThe show sticky data command retrieves the active sticky entries that have been dynamically learned. The value shown is not the actual cookie value, but a function of it created by Cisco ACE. Example configuration:switch/SAP-Datacenter# show sticky datasticky group : ep-cookietype : HTTP-COOKIEtimeout : 100 timeout-activeconns : FALSE sticky-entry rserver-instance time-to-expire flags ---------------------+--------------------------------+--------------+-------+

6026630525409626373 SAP-EP:50000 5983

switch/SAP-Datacenter# show sticky datasticky group : ep-cookietype : HTTP-COOKIEtimeout : 100 timeout-activeconns : FALSE sticky-entry rserver-instance time-to-expire flags ---------------------+--------------------------------+--------------+-------+

6026630525409626373 SAP-EP:50000 5938 -

Tuning the HTTP Header Parsing

When implementing cookie-based persistence, the Cisco ACE is parsing the HTTP header to look at the cookie. As a user browses through the portal, though, this header becomes quite large as SAP adds more cookies. By default Cisco ACE parses headers up to 2 KB, which is not enough. Headers larger than this are dropped, breaking the connection. The header errors can be seen from the show stats http command:switch/SAP-Datacenter# sh stat http

+------------------------------------------+

+-------------- HTTP statistics -----------++------------------------------------------+

LB parse result msgs sent : 151 , TCP data msgs sent : 152 Inspect parse result msgs : 0 , SSL data msgs sent : 495 sent TCP fin/rst msgs sent : 8 , Bounced fin/rst msgs sent: 8 SSL fin/rst msgs sent : 18 , Unproxy msgs sent : 14 Drain msgs sent : 118 , Particles read : 1718 Reuse msgs sent : 0 , HTTP requests : 156 Reproxied requests : 0 , Headers removed : 0 Headers inserted : 254 , HTTP redirects : 0 HTTP chunks : 37 , Pipelined requests : 0 HTTP unproxy conns : 14 , Pipeline flushes : 0 Whitespace appends : 0 , Second pass parsing : 0 Response entries recycled : 110 , Analysis errors : 0 Header insert errors : 0 , Max parselen errors : 3 Static parse errors : 0 , Resource errors : 0 Invalid path errors : 0 , Bad HTTP version errors : 0

It is essential to tune the header parsing to a larger value. A value of 4 KB was tested and worked well. Making this adjustment is done by defining a parameter-map and assigning it to the loadbalance policy. This same parameter map is used to add in other features such as persistence rebalance and Transmission Control Protocol (TCP) reuse.Example configuration:parameter-map type http persist set header-maxparse-length 4096

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Cisco ACE Module Implementation and Configuration class epSAP-s appl-parameter http advanced-options persist

SSL TerminationSSL sessions into a SAP server farm are often terminated by a network based appliance. This accomplishes several things. First, it is a requirement for cookie persistence since the HTTP header must be unencrypted to view the cookie. Similarly if the traffic must be inspected by an Intrusion Detection System (IDS), application level security device or other application layer analysis tool, it needs to be unencrypted. It also simplifies certificate management. So rather than having to purchase and install a cert on every server, it only must be done twice-on the Cisco ACE context and on the standby context. Note that certs are not automatically replicated in an HA configuration; they must be manually installed in the standby context. Figure 14 illustrates the SSL termination/offload process.

Figure 14 SSL Termination/Offload

To configure SSL termination, the first step is to acquire the private key and cert used to encrypt the sessions. For testing, the Cisco ACE can generate a private key and a certificate signing request which you can provide to a certificate authority to obtain a cert. Otherwise you can import the key and the cert using file transfer methods like FTP and TFTP or you can simply cut and paste it using the crypto terminal import command. To cut and paste a cert or key from one Cisco ACE module to another, use the crypto export filename terminal command to view it on the screen, then copy and paste it into the next module using the crypto import terminal command.Example configuration:switch/sap# crypto import ? ftp Import a key/certificate from an ftp server non-exportable Mark this key/certificate as non-exportable sftp Import a key/certificate from an sftp server terminal Accept a key/certificate from terminal tftp Import a key/certificate from a tftp server

The key and cert must be provided to Cisco ACE in the PEM format. If they are provided in another format such as PKCS#12, use a tool like OpenSSL to convert them to PEM. For more information, see http://gagravarr.org/writing/openssl-certs/general.shtml. If the files are imported properly, Cisco ACE will recognize whether the file is a key or a cert as shown in the last column of the following output example:switch/sap# show crypto filesFilename File File Expor Key/ Size Type table Cert-----------------------------------------------------------------------

NAM

Clear Text toServers:50xx0

Encrypted toVIP:443

IDS

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Cisco ACE Module Implementation and Configurationtestkey.key 497 PEM Yes KEYSAPcert.cer 855 PEM Yes CERT

You can verify that the cert matches the key with the crypto verify command:Cisco ACE-1/sap# crypto verify testkey.key SAPcert.cer Keypair in testkey.key matches certificate in SAPcert.cer.

Once the private key and cert are in place, create a proxy and attach it to the multi-match policy as follows:ssl-proxy service sap key testkey.key cert SAPcert.cer

policy-map multi-match SLB-policy class epSAP-s ssl-proxy server sap

This will cause the Cisco ACE to terminate the SSL and forward unencrypted HTTP to the server. At this point, the server has no way of knowing that the client has originated the session with SSL. As a result, the server issues 302 redirects as HTTP instead of HTTPS. See Figure 15. If the Cisco ACE is only accepting connections on port 443, it drops the HTTP request coming back from the client and the session is broken.

Figure 15 HTTP Redirects with SSL Offload

HTTP Header Rewrite (Cisco ACE 2.0)One option is to have Cisco ACE rewrite the header, which is available only in the Cisco ACE version 2.0. In this case the Cisco ACE examines every header response and when it sees HTTP, rewrites it as HTTPS. This is a feature implemented in the Cisco ACE 2.0 and is configured with an action-list assigned to the loadbalance policy.Example configuration:action-list type modify http ssl-only ssl url rewrite location ".*" sslport 443 clearport 80

policy-map type loadbalance http first-match ep class epL7 action ssl-only

https://----/irj

2231

20

https://----/irj

https://----/irj/

https://----/irj/index.html32Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationHTTP Header InsertA better approach that HTTP header rewrite is to take advantage of a custom header SAP has designed specifically for the SAP load-balancer doing offloadClientProtocol. When the SAP EP sees this header with a value of HTTPS, it knows to use HTTPS for the redirect, rather than HTTP. This is explained at the following URL:http://help.sap.com/saphelp_nw04s/helpdata/en/9a/53a2a4a45e244aa189c2b7065a0b78/content.htm. The Cisco ACE adds this header (available in Cisco ACE version 1.x) when the insert-http command is enabled on the loadbalance policy.Example configuration:policy-map type loadbalance first-match EP-HTTPS class class-default insert-http ClientProtocol header-value "https"

Persistence RebalanceAnother feature that should be enabled for either of the header rewrite or header insert options is persistence rebalance. Without persistence rebalance, a Cisco ACE only performs the header rewrite/insert on the first request of the connection. If there are multiple redirects in a connection, some will get missed and the SAP server will still send HTTP redirects. When persistence rebalance is enabled, the header is inserted into every request. This is done by adding another line to the parameter-map already established for header parsing.parameter-map type http persist set header-maxparse-length 4096 persistence-rebalance

policy-map multi-match SLB-policy class epSAP-s appl-parameter http advanced-options persist

Redirect ServerIf the policy is to only accept SSL connections to the server farm, the question becomes what to do with client requests for HTTP. As was shown above, the SAP server itself may redirect the client to HTTP if it does not realize the session originated as HTTPS. But there could also be other scenarios. The client may not know that HTTPS is a requirement and simply originate the connection as HTTP. There have also been cases where HTTP redirects are built into scripts by the server. One way to address all of these situations is with a redirect server. This way, anytime a client attempts to connect with HTTP, Cisco ACE can itself send a redirect to the client using a redirect server. This is done by creating a special redirect rserver and associating it with a policy that matches the same VIP address on port 80. When a request comes in from the client using HTTP it matches the redirect policy. This policy resolves to the redirect server which sends the HTTPS 302 to the client. This serves as a last line of defense so that if for any other reason an HTTP request comes in, it is redirected to HTTPS. The essential piece is the definition of the redirect server:rserver redirect anyHTTP webhost-redirection https://irj/portal 302 inserviceThis rserver must then be setup in a server farm, match a port 80 VIP, and match a load balancing and multimatch policy as shown in the following example:33Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and Configurationserverfarm host REDIRECT rserver anyHTTP inservice

class-map match-any HTTP-VIP match virtual-address 169.145.90.116 tcp eq www

policy-map type loadbalance first-match EP-HTTP-policy class class-default serverfarm REDIRECT

policy-map multi-match SAP-LB class HTTP-VIP loadbalance vip inservice loadbalance policy EP-HTTP-policy

Impact of TCP Reuse and SSL Termination on Server CPUWhen implementing SSL offload and TCP reuse together, server CPU utilization was improved. The amount of improvement increased with the transaction load. In the case of the DSL WAN, the transaction load was 16,000 transactions over a six-hour period and the CPU savings was 22 percent. When the transaction load was increased to 50,000 transactions the CPU savings was 50 percent. See Figure 16.

Figure 16 SAP EP CPU Utilization

Backend EncryptionIn some cases, the security policy requires that sessions are encrypted all the way to the server. With cookie persistence, however, the session must be decrypted to view the cookie. In this case Cisco ACE will decrypt the session, examine the header contents, make a server selection decision, and re-encrypt the session toward the server. See Figure 17.34Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationFigure 17 SSL Offload with Backend Encryption

This uses most of the same configuration as SSL offload without the header insert and can be enabled by adding in a client SSL proxy facing the server. It is configured by defining a proxy and assigning it to the loadbalance policy.Example configuration:ssl-proxy service testsslclient

policy-map type loadbalance first-match EP-HTTPS class class-default no insert-http ClientProtocol header-value "https" ssl-proxy client testsslclient

SSL Reuse (Cisco ACE 2.0)With the Cisco ACE version 2.0, SSL reuse can help on both sides of the connection. On the client side, SSL reuse reduces delay in the WAN by eliminating the round trip delays required for the key exchange. On the server side, SSL reuse reduces the performance penalty of SSL encryption. Without SSL session ID reuse, there is a constant process of renegotiating SSL session IDs. The most costly piece of this negotiation is the key exchange process, which uses asymmetric encryption. Once the keys are exchanged, the data encryption is symmetric and requires little additional CPU. By reducing the amount of asymmetric encryption taking place, most of the performance penalty associated with SSL on the server can be eliminated. Testing showed server CPU reduced by 24 percent with SSL reuse enabled. SSL session reuse is enabled in the Cisco ACE version 2.0 by creating an SSL parameter map and defining a timeout for the session-ID cache. Example configuration:parameter-map type ssl sslparams session-cache timeout 600

This parameter map must be assigned to the SSL proxy facing the client and the SSL proxy facing the server. Example configuration:ssl-proxy service testsslclient ssl advanced-options sslparams

ssl-proxy service sap key sap-private cert sap-cert ssl advanced-options sslparams

Use the show crypto session command to review the SSL session cache statistics. Example command output:switch/sap# show crypto session SSL Session Cache Stats for Context ------------------

SSL Initiation

Encrypted toServers:50xx1

SSL Termination

Encrypted toVIP:443

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Cisco ACE Module Implementation and ConfigurationNumber of Client Sessions 2Number of Server Sessions 4

TCP ReuseTCP reuse is used to reduce the amount of TCP connections to the server by sharing a pool of TCP connections across requests from multiple clients. See Figure 18. When a TCP connection is set up to the server, requests start to flow across it. For example, a Microsoft Internet Explorer (IE) browser will open up two TCP connections to the server and then load-balance all the individual object requests across those two connections. Without reuse, these TCP connections are only used by the client initiating the request.

Figure 18 TCP Connection Reuse

When TCP reuse is enabled, a TCP connection can be used by any client. When the Cisco ACE receives an object request from the client, it looks to see if there are any available TCP connections in the reuse pool and if one is available it uses it. If none are available, it sets up a new TCP connection. TCP connections are sent to the reuse pool when the server acknowledges a request, such as by returning a 200 OK. Until the time another request is sent across it, the TCP connection is available for reuse. The net effect is a reduction in the amount of memory required to service a given client load. If backend encryption is used, TCP reuse also improves server CPU performance by reducing the amount of encryption that needs to be donefewer TCP connections translates into fewer SSL sessions.

TCP2

TCP3

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22

ACE-TCP2 Pool2

ACE-TCP1 Pool1

TCP136Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationIn the testing with the Cisco ACE and the SAP EP, TCP reuse reduced the number of connections to EP by over 70 percent. See Figure 19.

Figure 19 TCP Reused with Cisco ACE and SAP EP

TCP reuse is configured by adding the server-conn reuse command to the same parameter map already used for header parsing and persistence rebalance:parameter-map type http persist set header-maxparse-length 4096 persistence-rebalance server-conn reuse

policy-map multi-match SLB-policy class epSAP-s appl-parameter http advanced-options persist

Source NAT for TCP Reuse

In order for TCP reuse to work properly, network address translation (NAT) is required on the client source IP address. In the example configuration that follows, a NAT pool is set up on the server VLAN interface. This NAT pool is activated when there is a match with the SAP-LB policy because of the nat dynamic command applied to the policy-map multi-match command. In this case, all traffic to the SSL-VIP with this policy will have the source IP address changed to 169.145.90.90.Example configuration:interface vlan 40 description server-EP nat-pool 123 169.145.90.90 169.145.90.90 netmask 255.255.255.255 patpolicy-map multi-match SLB-policy class SSL-VIP nat dynamic 123 vlan 20137Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationMonitoring TCP Reuse

The Cisco ACE tracks the number of times it used available pooled TCP connections as well as the number of events where there were no connections available in the TCP reuse pool. The following command displays results for one of the two network processors (NP) on the Cisco ACE module. Example configuration:Cisco ACE/dc# show np 1 me-stats -socm | i ReuseReuse retrieve link update conn invalid 0Reuse retrieve link update conn not on r 0Reuse retrieve success but conn invalid: 0Reuse retrieve miss: 2129Reuse conns retrieved: 255172

The Reuse retrieve miss counter increments when there was no connection available in the pool to reuse. When this happens, the Cisco ACE sets up a new TCP connection for the incoming request. The Reuse conns retrieved counter increments when there was a connection available in the pool, and the Cisco ACE reused it. Note there are two network processors (NPs); to see all events, output from a show on np2 command would be required as well. The -socm keyword means we are accessing statistics from the outbound connection manager. For a more real time view of connections in the pool versus total connections, compare the total connection count to the number of connections showing a reuse identifier. A show connection count command shows a total 544 connections. Of these, seven are flagged as in the reuse pool.Cisco ACE/dc# sh conn counttotal current connections : 544

Cisco ACE/dc# sh conn det | i reuse [ conn in reuse pool : TRUE] [ conn in reuse pool : FALSE] [ conn in reuse pool : TRUE] [ conn in reuse pool : FALSE] [ conn in reuse pool : TRUE] [ conn in reuse pool : FALSE] [ conn in reuse pool : FALSE] [ conn in reuse pool : TRUE] [ conn in reuse pool : TRUE] [ conn in reuse pool : TRUE] [ conn in reuse pool : TRUE]

Another way to gauge the amount of reuse occurring is to compare the connections to the VIP address in the show service-policy command output with the number of connections to the real servers in the show serverfarm command output.

WAN Tuning with Cisco ACEFor high-delay WAN environments, there is a big difference in latency between the server and the Cisco ACE on the LAN and between the Cisco ACE and the client across the WAN. Since the Cisco ACE is the device in the middle; it must either buffer the traffic or slow the server down using TCP flow control. The Cisco ACE software used in the design presented in this document(A1_6_2a) provides a minimal amount of buffering on the server side of this equation. Instead of using buffers to absorb spikes in the data, the default behavior is to rely primarily on TCP for flow control. This works; however, for the WAN environments tested herea 40 msec 768 Kbps link (also referred to as DSL) and a 300 msec T3 linkresponse time increased with the default settings on the Cisco ACE. Thus, the effect of excessive TCP flow control was to increase overall delayin spite of the fact that TCP reuse was enabled, which should have reduced delay.38Cisco Lean Retail SAP ERP Application Deployment Guide

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Cisco ACE Module Implementation and ConfigurationThe solution is to increase the buffer using the connection type parameter map as shown in the following configuration example:parameter-map type connection WAN set tcp buffer-share 262143

policy-map multi-match SLB-policy class SSL-VIP connection advanced-options WAN

With this change to the buffering, response time improved 16 or 39 percent, depending on the WAN scenario used. See Figure 20.

Figure 20 SAP EP Average Response Time

Another parameter that helps to improve response time in loss environments is selective acknowledgements. With selective acknowledgements enabled, less data is retransmitted across the WAN when packets are lost. This is enabled by adding to the parameter map shown above as follows:

parameter-map type connection WAN set tcp buffer-share 262143 tcp-options selective-ack allow

Optimization SummaryBeyond the basic configuration of rserver, server farm, probes, loadbalance policy, multimatch policy, and service policy, a number of variables were added to optimize the deployment of the SAP server farm as listed below:

Virtualization was used to speed deployment and provide distributed control to content owners. Health probes were customized to capture the health of application server and database. The loadbalance policy now refers to the sticky server farm which was created for cookie

persistence. It also inserts the custom SAP HTTP header required for SSL offload. The HTTP parameter map is used for TCP reuse, persistence rebalance (required for header insert),

and expanded header parsing (required for cookie inspection). 39Cisco Lean Retail SAP ERP Application Deployment Guide

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Application Security and Monitoring The WAN parameter map was created to reduce delay by moving flow control from TCP windows to buffers as well as reducing retransmissions in the event of loss.

Source-NAT is applied to the server VLAN interface to ensure good performance for TCP reuse. SSL reuse is used in 2.0 environments to reduce WAN traffic and speed response time in SSL offload

topologies as well as to reduce server CPU when backend SSL is employed. A redirect server is used when only encrypted traffic is allowed into the server farm. It corrects the

incorrectly typed URLs and provides a last line of defense when embedded scripts redirect formerly encrypted connections to HTTP.

Figure 21 shows how these various optimizations map to the multi-match policy.

Figure 21 SAP Server Farm Deployment Optimization

Application Security and MonitoringThis section addresses application security with the Cisco ACE XML Gateway as well as server monitoring and troubleshooting with the Cisco Network Analysis Module. It includes the following topics:

Application Security with the Cisco ACE XML Gateway, page 41 Server Monitoring and Troubleshooting, page 43 Cisco NAM SetupInitial Cisco NAM Configuration, page 45

SSL Termination

parameter-map type http PERSISTserver-conn reusepersistence-rebalanceset header-maxparse-length 4096

parameter-map type connection WANset tcp buffer-share 262143

interface vlan 40description server-EPaccess-group input ANYnat-pool 123 169.145.90.90

169.145.90.90 netmask 255.255.255.255 pat

Parameter Maps

Source NAT

Multi-match Policypolicy-map multi-match SLB-policy

class SSL-VIP loadbalance vip inserviceloadbalance policy EP-HTTPS loadbalance vip icmp-replynat dynamic 123 vlan 201 appl-parameter http advanced-options PERSISTssl-proxy server EPconnection advanced-options WAN

class REDIRECT loadbalance vip inserviceloadbalance policy REDIRECT

ssl-proxy service EPkey testkey.keycert SAPcert.cerssl advanced-options sslparams

parameter-map type ssl sslparams

session-cache timeout 600

SSL Reuse (2.0)

policy-map type loadbalance http first-match EP-HTTPSclass class-defaultsticky-serverfarm ep-learn

insert-http ClientProtocol header-value "https"

Persistence and Header Insert

rserver redirect anyHTTP webhost-redirection

https://irj/portal 302inservice

Redirect Server

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Application Security and MonitoringApplication Security with the Cisco ACE XML GatewayThe Cisco ACE XML Gateway (AXG) is shown as the application gateway in this design. It provides a full Layer-7 proxy and includes integrated XML security for web services transactions. Without XML security in place, web services communications are vulnerable to a number of attacks. For example, an SAP ERP server running web services was attacked by simply overriding the schema and placing a 5 MB data load where the schema provided for just a few bytes. See Figure 22.

Figure 22 Denial-of-Service Attack with XML Schema Violation

Since schema validation was not enabled on the server, server CPU went from 0 to 30

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